First try this unplug the kill wire off the coil and see if it is grounding out. If that is not then the coil and magnet might have some rust on them. You might want to pull the coil off and sand the rust off of the flywheel end of it and the sand the magnet down to remove the rust and reset the gap between the coil and flywheel with a business card. The only other thing I can think of the coil might be bad.
